public class MainActivity extends Activity {
    private PopupWindow pop; 
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test);
        
        //将layout的xml布局文件实例化为View类对象
        LayoutInflater inflater =LayoutInflater.from(this);        
        View view =inflater.inflate(R.layout.mypop, null);
        
        //创建PopupWindow，参数为显示对象，宽，高
        final PopupWindow pop =new PopupWindow(view, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        

        //PopupWindow的设置
        pop.setBackgroundDrawable(new BitmapDrawable());        
        //点击外边消失
        pop.setOutsideTouchable(true);      
        //设置此参数获得焦点，否则无法点击 
        pop.setFocusable(true);
        
        //设置文本监听事件
        TextView text =(TextView) findViewById(R.id.topmenu);
        text.setOnClickListener(new OnClickListener(){

            @Override
            //判断是否已经显示，点击时如显示则隐藏，隐藏则显示
            public void onClick(View v) {
                if(pop.isShowing()){
                    pop.dismiss();
                }else{
                    pop.showAsDropDown(v);
                }
                
            }

                    
            
        });